1. Technical Field
The present invention relates to an engine and more particularly it concerns an engine able to enhance the strength of a crank case.
2. Earlier Technology
There is a conventional example of this engine which comprises a crank case provided with a lower opening portion, which is covered with an oil pan from below, and with a pair of left and right oil passages which extends in a front and rear direction along left and right lateral walls of the crank case, as well as the present invention
The engine of this kind has an advantage to facilitate its production since it dispenses with external pipings for the left and right oil passages.
However, the conventional engine provides left and right ribs on the left and right lateral walls of the crank case, which extend in the left and right direction. These left and right ribs are raised inwardly from the left and right lateral walls of the crank case. In order to provide left and right oil passages in these left and right ribs, these left and right ribs are positioned higher than the lower opening portion of the crank case. This causes problems.
The above-mentioned prior art has the following problems.
<Problem> The lower opening portion of the crank case has a peripheral wall of a low strength.
Since the left and right ribs are positioned higher than the lower opening portion of the crank case, the lower portion of the crank case is low in the strength of its peripheral wall. This invites an insufficient strength of the whole crank case and also a difficulty of attempting to increase output.
<Problem> It is impossible to enlarge a rotation radius of a crank pin.
Due to the fact that the left and right ribs are positioned higher than the lower opening portion of the crank case, if the rotation radius of the crank pin is enlarged, it entails a likelihood that a larger-diameter portion of a connecting rod interferes with them. For this reason, it is necessary to decrease the rotation radius of the crank pin with the result of being unable to lengthen the stroke of a piston so as to increase the output of the engine.
<Problem> There is a case where lubricity becomes insufficient.
In the event that the left and right ribs are made small so as to avoid the interference with the larger-diameter portion of the connecting rod, it is impossible to sufficiently increase the sectional area of each of the left and right oil passages, In this case, the lubricity becomes so insufficient that the engine cannot cope with the sliding resistance of every sliding portion which increases along with the increase of output.
The present invention has an object to provide an engine capable of solving the above-mentioned problems and more particularly, to provide an engine able to increase the strength of the crank case.
The characteristic matter of the invention as set forth in claim 1 is as follows.
As exemplified in FIGS. 1, 2 and 3(A), an engine comprises a crank case 1 provided with a lower opening portion 2, which is covered with an oil pan 3 from below, and, on the assumption that a direction where a crank shaft 4 spans is a front and rear direction and that a widthwise direction of the crank case 1 is a left and right direction, it is provided with a pair of left and right oil passages 7, 8 which extends in the front and rear direction along left and right lateral walls 5 and 6. In this engine, as exemplified in FIGS. 2 and 3(A), the left and right lateral walls 5 and 6 of the crank case 1 are provided with left and right ribs 12 and 13, respectively which extend in the front and rear direction. These left and right ribs 12 and 13 are raised from the left and right lateral walls 5 and 6 of the crank case 1. In order to form left and right oil passages 7 and 8 in these left and right ribs 12 and 13, these left and right ribs 12 and 13 are positioned at the lower opening portion 2 of the crank case 1.
(Invention of Claim 1)
Effect> The lower opening portion of the crank case has a peripheral wall of a high strength.
As illustrated in FIGS. 2 and 3(A), since the left and right ribs 12 and 13 are positioned at the lower opening portion 2 of the crank case 1, the lower opening portion 2 of the crank case 1 is high in the strength of the peripheral wall. This results in the possibility of enhancing the entire strength of the crank case 1 in an attempt to increase the output.
<Effect> It is possible to enlarge the rotation radius of the crank pin.
As exemplified in FIG. 2, owing to the fact that the left and right ribs 12 and 13 are positioned at the lower opening portion 2 of the crank case 1, even if the rotation radius of the crank pin 17 is enlarged, there is no likelihood that the larger-diameter portion 33 of the connecting rod interferes with them. Thus it is possible to enlarge the rotation radius of the crank pin 17 and lengthen the stroke of the piston with the result of being able to attempt to increase the output.
<Effect> It is possible to enhance the lubricity.
As shown in FIG. 2, the left and right ribs 12 and 13 can be largely raised without fearing the interference with the larger-diameter portion 33 of the connecting rod. Therefore, the left and right oil passages 7 and 8 provided internally of these ribs 7 and 8 can increase their sectional areas to sufficient ones and can enhance the lubricity, which in turn results in the possibility of coping with the sliding resistance of every sliding portion which increases along with the enhancement of the output.
(Invention of Claim 2)
It offers the following effect in addition to those of the invention as set forth in claim 1.
<Effect> It is possible to increase the rotation radius of the crank pin.
As exemplified in FIGS. 2, 4 and 5, the rotation radius from a center axis 4a of the crank shaft 4 to the outermost portion of the crank pin 17 is made larger than an inner diameter of each of intermediate bearing holes 14a, 15a and of an end bearing hole 16a. The intermediate bearing holes 14a and 15a have peripheral edge portions provided with recesses 14d and 15d and also the end bearing hole 16a is provided with a recess 16d, thereby enabling the outermost portion of the crank pin 17 to pass through every recess 14d, 15d and 16d upon accommodating the crank shaft 4 in the crank case 1. This makes it possible to increase the rotation radius of the crank pin 17 and elongate the stroke of the piston in an attempt to increase the output.
(Invention of Claim 3)
It offers the following effect in addition to that of the invention as set forth in claim 2.
<Effect> It is possible to inhibit the disadvantage of splashing up the oil by the crank shaft.
As illustrated in FIGS. 2 and 5, the recesses 14d and 15d of the intermediate bearing holes 14a and 15a are arranged at an upper side portion of the intermediate bearing holes 14a and 15a. This prevents the recesses 14d and 15d from being clogged by waved oil within the oil pan 3 to result in always communicating the respective partitioned chambers of the crank case 1 with each other through the recesses 14d and 15d. Further, it levels the pressure variation of every partitioned chamber, caused through pumping of the piston. This prohibits the disadvantage of splashing up the oil 9, which has floated up due to the pressure variation in every partitioned chamber, by the crank shaft 4, which in turn inhibits the loss of horse power, the oil deterioration and the oil consumption.
(Invention of Claim 4)
It offers the following effect in addition to those of the invention as set forth in claim 1.
<Effect> The lower opening portion of the crank case has a peripheral wall of high strength.
As shown in FIG. 3(B), a reference hole 18 communicated with either of the left and right oil passages 7 and 8 is sealed by a steel ball 20 struck thereinto after having worked the cylinder block 19. Consequently, when compared with the case where this is sealed by a cup-like plug, the lower opening portion 2 of the crank case 1 has a peripheral wall of higher strength.
(Invention of Claim 5)
It offers the following effect in addition to those of the invention as set forth in claim 1.
<Effect> It is possible to increase the amount of oil within the oil pan.
As exemplified in FIG. 1, the oil pan 3 is extended up to below a timing gear case 21 to result in the possibility of increasing the amount of oil 9 able to be stored in the oil pan 3. Thus it is possible to cope with the sliding resistance of every sliding portion which increases along with the enhancement of the output.
<Effect> It is possible to increase the strength of the oil pan.
As exemplified in FIG. 1, the oil pan 3 is extended up to below the timing gear case 21. The thus extended portion 3a of the oil pan 3 has an upper end attached to a lower end portion 21a of the timing gear case 21 with the result of being able to increase the strength of the oil pan 3.
(Invention of Claim 6)
It offers the following effect in addition to that of claim 5.
<Effect> It is possible to effectively utilize the timing gear case as a portion for attaching an auxiliary machine.
As exemplified in FIG. 6(A), when seen in a direction parallel to a center axis 4a of the crank shaft 4, the timing gear case 21 has a lower portion projected more laterally than the lateral wall 6 of the crank case 1. This more laterally projected portion 21b of the timing gear case 21 is provided with a seat 22 for attaching the auxiliary machine 23. Accordingly, it is possible to effectively utilize the timing gear case 21 as the portion for attaching the auxiliary machine 23.
(Invention of Claim 7)
It offers the following effect in addition to that of the invention as set forth in claim 6.
<Effect> It is possible to effectively utilize a lateral side of the crank case as a space for accommodating the auxiliary machine.
As exemplified in FIG. 7, the seat 22 for attaching the auxiliary machine 23 is provided at a rear portion of the laterally projected portion 21b and the auxiliary machine 23 attached to the seat 22 for attaching the same is made to position along the lateral wall 6 of the crank case 1. Therefore, it is possible to effectively utilize the lateral side of the crank case 1 as the space for accommodating the auxiliary machine 23.
(Invention of Claim 8)
It offers the following effect in addition to that of the invention as set forth in claim 6.
<Effect> It is possible to seal an overlapping portion and to attach a first idling gear at the same time.
As exemplified in FIGS. 7 and 9, there is arranged a first idling gear 26 between a crank gear 24 and an input gear 25 for the auxiliary machine 23. The timing gear case 21 has a rear wall 17 composed of an overlapping portion 27a, which overlaps a front wall 28 of the crank case 1, and a portion 27b which laterally projects from the front wall 28 of the crank case 1. The overlapping portion 27a is fixed in pressure-contact with the front wall 28 of the crank case 1 through a fastening force of a bolt 26a for attaching the first idling gear 26. Consequently, it is possible to seal the overlapping portion 27a with respect to the front wall 28 of the crank case and to attach the idling gear 26 simultaneously.
(Invention of Claim 9)
It offers the following effects in addition to that of the invention as set forth in claim 8.
<Effect> It is possible to enhance the strength of the timing gear case.
As shown in FIGS. 6(B) and 6(C), a closure 29 for an opening portion 21c is formed with a rib 29a. This can enhance the strength of the closure 29 and in turn the strength of the timing gear case 21. Thus even if the driving reaction force of the auxiliary machine 23 is strong, the timing gear case 21 can receive it.
<Effect> It is possible to effectively utilize the rib for a wall of the oil passage.
As exemplified in FIG. 6(B), the rib 29a is internally provided with an oil passage 29b. Therefore, the rib 29a can be effectively utilized as the wall of the oil passage.
(Invention of Claim 10)
It offers the following effect in addition to that of the invention as set forth in claim 9.
<Effect> It is possible to more enhance the strength of the timing gear case.
As exemplified in FIGS. 6(B) and 6(C), the rib 29a of the closure 29 is formed so that it is bent along a surface of the closure 29. This results in the possibility of more enhancing the strength of the timing gear case 21. Thus the timing gear case 21 can receive the stronger driving reaction force of the auxiliary machine 23.
(Invention of Claim 11)
It offers the following effect in addition to that of the invention as set forth in claim 8.
<Effect> It is possible to attach a second idling gear and to fix the seat for attaching the auxiliary machine at the same time.
As exemplified in FIG. 7, there is provided a second idling gear 0 between the first idling gear 26 and the input gear 25 for the auxiliary machine 23. The seat 22 for attaching the auxiliary machine 23 is made to position along the laterally projected portion 27b of the rear wall 27 of the timing gear case 21 and is fixed thereto by a tightening force of a bolt 30a for attaching the second idling gear 30. This makes it possible to simultaneously attach the second idling gear 30 and to fix the seat 22 for attaching the auxiliary machine 23 with the result of enhancing the workability when assembling the engine.
(Invention of Claim 12)
It offers the following effect in addition to that of the invention as set forth in claim 11.
<Effect> Lubricity is high at a portion where gears mesh with each other.
As shown in FIG. 9, a gear accommodating chamber 31 which accommodate the input gear 25 for the auxiliary machine 23 has a bottom 31a where oil stays. The oil is lifted up along an inner peripheral surface of the gear accommodating chamber 31 through the rotation of the input gear 25 for the auxiliary machine 23 and is supplied from above to a portion 32 where the second idling gear 30 meshes with the input gear 25 for the auxiliary machine 23. Therefore, the portion 32 has so high a lubricity that even if the portion 32 receives the strong driving reaction force of the auxiliary machine, it is prevented from being worn off.
(Invention of Claim 13)
It offers the following effect in addition to those of the invention as set forth in claim 1.
<Effect> It is possible to make the engine compact.
As illustrated in FIG. 7, the auxiliary machine 23 is a hydraulic pump which gives output against the external load applied to the engine. Consequently, when compared with the case where output is given by a wrapping transmission device or the like, the engine can be made compact.